This application claims benefit of Japanese Application No. 2000-032153 filed in Japan on Feb. 9, 2000, the contents of which are incorporated by this reference.
1. Field of the Invention
This invention relates to a distance measuring device, and more particularly to a distance measuring device having area sensing means deployed at the focal point position(s) of a pair of image formation optical systems.
2. Description of the Related Art
More and more cameras are being provided with autofocus functions in recent years, being configured so that the distance to the object is detected by a distance measuring device, and the photographic lens is moved to a focus position based on the results of that detection.
When measuring the distance to an object by such a distance measuring device, in addition to distance measuring devices wherewith ranging is made only in a limited region in the center of the screen, distance measuring devices have come to be known in recent years which have a wider field of view.
In Japanese Patent Application Laid-Open No. H10-104502/1998 (published), for example, a type of such a distance measuring device having a wide-range field of view is described which divides the image pick-up region of a two-dimensional area sensor into a plurality of areas, and performs integration control based on a maximum accumulation quantity pixel signal for each divided area.
And in Japanese Patent Application Laid-Open No. H10-126679/1988 (published) is described a distance measuring device that deploys a monitor sensor so as to enclose the periphery of a two-dimensional area sensor, and performs integration control on the area sensor overall based on outputs from that monitor sensor.
The distance measuring device described in Japanese Patent Application Laid-Open No. H10-104502/1988 (published), however, is object to the following problems.
That is, means are employed for referencing a maximum value inside the area of each divided area, sequentially, divided area by divided area, stopping the integration when an appropriate integral quantity has been arrived at in each divided area. Wherefore, when the object is a high-brightness object, saturation can occur before the integration control can be effected.
In order to cope with this problem, a high-speed control circuit or area sensor circuit may be employed. In that case, however, costs are increased, wherefore such application ceases to be suitable for a small size instrument such as a compact camera, for example.
Furthermore, because the method of dividing the area is fixed, in cases where one object covers a plurality of division areas, a problem arises in that the integration quantity differs from one portion of that same object to another, whereupon image data are produced which are not suitable to the detection of the primary object.
With the art described in Japanese Patent Application Laid-Open No. H10-126679/1988 (published), on the other hand, the positions of the two-dimensional area sensor and monitor sensor differ, wherefore, when the two-dimensional area sensor and monitor sensor sense different object images, even if appropriate control is effected according to the output of the monitor sensor, problems arise, such as the area sensor integral quantity being too great so that saturation is reached, or, conversely, such as the integration being insufficient, so that appropriate object image data cannot be obtained.
Also, in cases where the accumulation quantity reaches saturation or is insufficient, integration will be performed repeatedly, wherefore the time lag will increase, which is also a problem.
An object of the present invention is to provide an inexpensive distance measuring device with which appropriate integration control can be effected across the entirety of a wide-range ranging region, and wherewith the time lag is short.
The present invention, substantially, is a distance measuring device comprising: two optical systems exhibiting parallax; an image pick-up element for photographically capturing two images formed by the abovementioned optical systems; region setting means for setting divided regions based on output from the abovementioned image pick-up element; integration control means for controlling integration operations of the abovementioned image pick-up element according to divided regions produced by the abovementioned region division means; and distance measurement means for performing distance measurements based on output from the abovementioned image pick-up element.
The present invention, moreover, is a distance measuring device comprising: an area sensor deployed in the vicinity of position of focal points of a pair of image forming optical systems, and having a pair of light receiving regions; a region dividing unit for dividing each of light receiving regions of the abovementioned area sensor means into a plurality of regions according to area sensor data obtained from results of preliminary integrations of the abovementioned area sensor means; and a control circuit for causing the abovementioned area sensor to perform final integration operations for each of the abovementioned set plurality of light receiving regions, and for computing signals for putting a photographic lens into a focused condition based on data obtained for each of the abovementioned plurality of light receiving regions.
The present invention, furthermore, is a distance measuring device comprising: an area sensor deployed in the vicinity of focal points of a pair of image forming optical systems, and having a pair of light receiving regions; main photographic object detection means for detecting region where main photographic object is present; region division means for setting light receiving regions of the abovementioned area sensor based on output of the abovementioned main photographic object detection means; and control means for causing the abovementioned area sensor means to perform final integration operations for each of the abovementioned set light receiving regions, and performing distance measurement computations based on data obtained for each of those light receiving regions.
Still further, the present invention is a control method for a camera that puts a photographic lens into a focused condition for a main photographic object in an image pick-up screen, comprising the steps of: detecting image signals in the abovementioned image pick-up screen; detecting the abovementioned main photographic object based on the abovementioned image signals; setting a virtual area inside the abovementioned image pick-up screen so as to contain the abovementioned detected main photographic object; again detecting image signals in the abovementioned virtual area; computing signals for putting the abovementioned photographic lens into a focused condition based on the abovementioned re-detected image signals; and putting the abovementioned photographic lens in a focused condition based on results of the abovementioned computation.
These object(s) and advantages of the present invention will become further apparent from the following detailed explanation.